Figure 1.

A, Devaluation testing: experiment 1. After stable acquisition of the drug seeking/taking chained schedule, the cocaine taking link was devalued by extinction. Responses on the drug seeking lever and head entries into the sucrose magazine were measured under extinction conditions during 5 min tests before and after revaluation of the drug taking link (arrows) by two sessions where cocaine infusions were available again under an FR1 schedule. B, Cocaine seeking responses and head entries into the sucrose magazine during tests conducted under devalued and revalued conditions. C, The magnitude of the devaluation effect was calculated as cocaine seeking responses after devaluation expressed as a percentage of seeking responses under the revalued condition for each animal (filled circles, n = 14). Percentage of seeking responses under the revalued condition is plotted for each animal. The average ± SEM for the group (solid horizontal line) is also shown. All data are expressed as the mean ± SEM. *p < 0.05, paired t test.